


Tough Love

by RomaStache



Category: Undertale (Video Game)
Genre: A lot of this would be better if you just TALKED to one another, Alternate Universe - Underswap, Gen, Not your typical Blueberry btw, Sans Has Issues, Underswap Papyrus, Underswap Sans, Worried Papyrus, jokes about weed
Language: English
Status: In-Progress
Published: 2018-01-09
Updated: 2018-06-12
Packaged: 2019-03-02 18:37:13
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 7,212
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13324110
Author URL: https://archiveofourown.org/users/RomaStache/pseuds/RomaStache
Summary: Here: Sans and Papyrus have a fight. It doesn’t end the way they expect.And There: Sans and Papyrus have been fighting for a long, long time. They fight again- and it doesn’t end well. But. At least it doesn’t end.And Yonder: Sans is very, very tired, but he can’t stop fighting- not when Papyrus and Undyne are depending on him. He wishes the universe would throw him a bone- it throws him 824. None of them do him any good.Everywhere: Across space and time, there are always some constants- Sans and Papyrus are brothers. They’re not the ones in control. Things get messier before they get better. No one knows what’s going to happen next.(Alternatively: Sans and Papyrus have an argument that's been building for a while, and end up taking a cross-universe field trip. They learn: Everyone has a cross to bear. Everyone’s doing their best to deal with it. Even when they obviously can't handle it, trying to help can make it much, much worse.)





	1. Reverse Trick-or-Treating

**Author's Note:**

> For clarification:  
> Underswap!Sans - Sansy  
> Underswap!Papyrus - Pappy  
> Undertale!Papyrus - Papyrus (Pap)  
> Undertale!Sans - Sans

Papyrus would happily admit there were a lot of things he did not understand, especially about his brother. He chugged bottles of Ketchup like soda, used his magic of time and space manipulation for pranks, and had a strange fascination with puns, particularly of the skeleton variety. They were all the things that were Sans, and Papyrus cherished their differences, particularly now that they were on the surface and Sans was significantly happier. But…  
  
He certainly didn’t make it _easy_.

“Yeah, uh, I can’t find it, buddy. Weird, since you… laid it out really obviously, on the blood splattered tablecloth by the cobwebs. Really, uh, helpful. Thanks. Sorry. Uh, look, why don’t you go ahead and I’ll Ketch-up-”

“No! The whole point of _matching_ costumes is that we _match_ ! It would look utterly ridiculous if I just went by myself!”  
  
“I can understand your _fiery_ passion for _matching_ costumes, but it’ll be great bro. Didn’t stop you Underground, won’t stop you now.”

“Don’t try and pun your way out of this!”

It was their first Halloween on the surface and Papyrus decided to dust off his old battle body for Toriel’s Halloween party, but somehow it ended with a faceoff against Sans just as they were preparing to leave. Disappointment in Sans for having “misplaced” his costume and dealing with his weird moodiness since leaving the Underground had been building up for too long, culminating in a long overdue argument. Er, _discussion.  
_  
“I have had it up to here with you, Sans! Not only have you misplaced the costume we both spent ages working on, for the party I have been telling you about for at LEAST a week, but you can’t even be bothered to use one of your blasted shortcuts to go find it! Which you _shouldn’t,_ given how obviously dangerous they are, but your priorities are completely out of line-” 

Sans tensed immediately, giving Papyrus a sharp glare before looking away like a sulky child.

“I didn’t want to do this now, but I can’t forgive reckless endangerment just like that! I just can’t believe how irresponsible you can be! I don’t care how many times you've used them or how they work, you need to be more careful!”  
  
“Ok, ok! I really freaked you out- sorry, for like the fiftieth time. Chill out! It’s not that big of a deal,” Sans answered testily, patience wearing thin. He _knew_ what he was doing- Papyrus didn’t even really understand how shortcuts worked! Who was he to lecture him on shortcuts?  
 

“Of course it’s a big deal- you fell asleep! Mid shortcut! I'd be impressed if I wasn't fighting off the heart attack from you nearly teleporting yourself to oblivion!” 

“What do you want to hear?” Sans snapped, “ I’ll never do it again? I’ll limit my magic to only absolute emergencies? Wait, I got it:, I’ll lock myself in a padded tower like a princess, where nothing can ever happen to my frail, glass-like body, ‘cause I’ll have the GREATEST guardsman ever, right, except-”  
  
As his temper flared, Sans was automatically dipping into sarcasm, looking up at Papyrus with every intent to fight- before clamping his mouth shut.  What was he doing? This was Papyrus, his little brother and best friend- not some grim, grinning ghost he needed to tear down with words and negativity. Guilt gnawed at his soul as he worried at the threadbare spot on the carpet with the corner of his slipper, keeping his eyes firmly glued to the floor as irritation and frustration continued to fester in his bones. 

“Except _what_ , Sans?!”  
  
It had been a rough couple of days, wrestling with inner demons that had been resuscitated by the inescapable visions of bloodied zombies and headless horsemen. Everywhere he seemed to go was filled with the echoes of screams and laughter, darkness and cobwebs and dust and blood that seemed to pervade his every waking moment- even his own home.

Sans didn’t have the heart to tell such an enthusiastic Papyrus that the ‘suitably spookified’ house left him feeling cold, plaguing his sleep with nightmares he thought couldn’t scare him anymore. It was literally the last day of this god-awful month, the culmination of all the spookiness and horror that would soon be flushed out in an immediate cascade of white trees and sparkling ornaments and tiny jingles that felt much more like home. He couldn’t _wait_ .

“Sans!”   
  
How could he tell Papyrus he would rather die than go to Toriel’s house for a Halloween party, where he would inevitably see a demon in an innocent child? How could he explain that he was terrified he wouldn’t be able to keep the here and now separate from the fuzzy past, and that he couldn’t trust himself not to do something they would all end up regretting? 

“Sans! Are you ignoring me?!” Papyrus crossed his arms and frowned, unnerved by Sans’ sudden silence. His brother didn’t so much as look up.

Sans had hoped that the mysterious disappearance of his Halloween costume, and his purposefully infuriating behavior lately, would be enough to have Papyrus just ditch him at home in a fit of frustration…. But it seemed that words weren’t going to cut it this time.

“Ugh!” When it was clear Sans wasn’t going to say anything, Papyrus sighed in unhappy defeat.

“Fine, fine! Don’t wear your laboriously, lovingly constructed costume to the party _all our friends_ have _painstakingly_ put together for everyone’s enjoyment! But we’re leaving now so we can arrive there on time, _in my car_ \- since someone doesn’t understand that using ‘shortcuts’ for every fleeting whim has consequences!” 

This argument clearly wasn't going anywhere and they hardly had the time for it if they wanted to get to the party on time- and it probably would have been a good idea to drop the subject- but Papyrus refused to budge until he got it through his brother's thick skull.

“Ok, _Mom_ ,” Sans focused on his feelings of annoyance as he grabbed Papyrus’ hand with a little more force than was necessary, focusing his magic on the door to create a shortcut that would take them right into Toriel’s kitchen. The last place he wanted to go. 

Papyrus let out an indignant huff as his hand was wrestled in a tight grip, looking at the undulating, discolored magic seeping from under the doorway in front of him with distaste. “What are you doing, we have a party to get to-!”

“Let’s go on a little field trip! I’ll show you exactly how these work so you’ll get why it’s perfectly safe and why you don’t need to worry about it.” Sans wrenched the door open, and shot him a flat look. “And we’ll get you to your _precious party_ fashionably early.” 

“ _My-_ ?! Unbelievable! It's like you haven't been listening to a word I've been saying all along! Let go, I refuse to be a part of this!”

Sans had methods of getting things to go his way, a solid yank causing Papyrus to stumble and follow him through the shortcut with barely any time to brace himself.  
  
It felt as unusual and unpleasant as the past handful of times he had done it, and Papyrus emerged extremely unhappy. It was still the living room, and though the wallpaper seemed somewhat off, Papyrus was too irritated to care.  
  
“That didn't prove anything! Agh! Why do you always have to be so difficult?!” Papyrus snatched his hand back, glaring down at Sans for all of two seconds before he sighed. He was getting tired of arguing. “...Listen, Sans... I know you know what you're doing. You know your magic better than I do, after all. I'm just worried because...well, what do I do if you do get trapped in one of your shortcuts? How am I going to help you?”

Sans sighed, rubbing the back of his skull as he nodded guiltily. Ok, that hadn’t been particularly nice and he should have known better than to let his emotions get the better of him. “Yeah…”

Self-hatred burned in his soul-  Papyrus was coming from a place of love, how could he try to punish his brother for caring about him? After all, it wasn’t Papyrus’ fault he was jumping at shadows, and how could he expect his brother to understand his reticent behavior when he wouldn’t explain himself? Sans wanted to dig a hole and bury himself in it for the next few years.  
  
“You’re right, Pap, I’m sorry. That was-”  
  
“Hey uh, not to interrupt, but did you guys have to teleport in front of the TV?”  
  
The other voice startled Sans so badly he actually jumped, so tightly coiled from the stress and emotional exhaustion of the last few days that his magic immediately flared to life. Sans was in a half crouch, both hands out of his pocket as unformed magic rolled off his twitching fingertips, frantically looking at-

Papyrus. Papyrus??? Slouched lazily against the couch, a variety of food stains decorating his orange hoodie and shorts, his jaw was positioned into a permanent tired smile with a toothpick sticking out- it was Papyrus’ face and body, but with Sans’ demeanor.  
  
“Sans,” Papyrus hissed after a moment, “what's going on? Is this… a prank?” 

The other Papyrus similarly looked him up and down before looking at Sans, eyes widening comically. The stick poking out of his mouth was nearly swallowed before he removed the toothpick with a wheeze, coughing violently. 

Sans snapped out of his stupor when he was addressed, whipping his head back to look at his brother. Sans’ lifted a shaking hand to his brother’s chest, feeling the soft fabric bunch under his fingers and the firm ribs underneath as he gave a gentle push. Sans then immediately whipped his head back as other Papyrus tried to stop coughing. 

“Pap, I think I’m more tired than I thought- I’m… seeing double.” 

Sans was used to vivid nightmares- hallucinations were new to him. He rubbed at his sockets with the heels of his palms roughly enough to gouge his eyes out- if he had any. He blinked blearily, but the Sans-like Papyrus (Comic Papyrus?) was still there. Sans’ smile tightened as the anxiety and stress bubbling up in his chest made it very, very hard to keep cool and collected. 

“Sans,” Papyrus tried again, alarmed when his brother plastered himself against Papyrus’ legs, as if afraid Papyrus would vanish, shaking ever so slightly. Never taking his eyes off of the doppelganger on the couch. “Who is he? Why is he in our house?”  
  
“Pap, you’re absolutely right about everything- I’m an idiot, a worthless brother and I’m really sorry,” Sans spoke in a rush as he hurriedly took in their surroundings. The walls were a slightly different color, the couch was a different style, and his sock wasn’t where he had last left it. There weren’t any Halloween decorations, and the darkness outside was too deep and even to be the tail end of the sunset they just left. 

“This isn’t our house.”  
  
Sans’ confusion and alarm were starting to scare Papyrus, feeling the spike in his brother’s magic with concern. His brother’s ominous statement had him look between Sans and the couch doppelganger. "Wait, what?"  
  
“Pappy, who are you talking to-? ”  
  
Sans froze as a new voice called out from the kitchen, sounding painfully familiar but with the absolute wrong cadence and intonation, and he gripped Papyrus’ leg like a lifeline as he very slowly creaked his head to the side… And locked eyes with a shorter, stockier skeleton who he had only seen on the other side of the mirror.  
  
“Through the looking glass, darkly,” he murmured to himself, letting out a small chuckle that had the other Sans go from startled to alarmed. Although the frilly pink apron seemed innocuous, Sans could clearly pick out the details of a ‘battle body’ that seemed much more combat-oriented than his brother’s costume. He was holding a ... a spoon with yellow sauce on it?  
  
Sans could not deal with that today.

With a tensing of his shoulders the only warning Papyrus got, Sans quickly opened  the door, and shoved Papyrus through, slamming it shut behind them. 

“There’s no place like home, there’s no place like home-” Sans murmured to himself like a prayer, concentrating on the familiar- the beat up, lumpy green sofa, those old stairs that always squeaked on the 3rd and 7th step, the hideous blue and purple carpet. His magic reached out and seemed so close to reaching out to home, but each time he wrenched the door open, it was the same living room. 

Papyrus watched in horrified fascination as Sans opened and closed the door in rapid succession, magic forming around the doorway in writhing wisps, switching from magenta, yellow, and blue and… not doing anything. Whatever anger he felt disappeared as he placed a gentle but firm hand on his brother’s shoulder, pulling him back a step away from the door. 

“Sans…?” he inquired softly, unease and confusion making his soul feel unpleasantly heavy as he turned Sans around. His brother swayed unsteadily, dizzy from the intense, prolonged magical output and probably disoriented too. There was a sheen on his forehead, almost as though he had been sweating. 

“Why…?” Sans started to ask, and Papyrus pulled him into a tight hug, shrugging helplessly. This was precisely why he hated shortcuts. The door slammed open again and a hand fisted itself into the back of Sans’ hoodie. Papyrus dug his heels into the worn welcome mat and pulled against the force trying to pull them in- 

Only for another hand to grab him by the shoulder and pick him off the floor, literally throwing him inside. Sans might have screamed a little bit- or was that him? Papyrus managed to catch himself before the momentum forced him face-first into the side to the couch, soul thundering in his chest as he looked at the other Sans warily. The TV behind them was playing a TV show, but it wasn't Mettaton. 

“You’re… really strong,” Papyrus tried to sound neutral and calming, but it was hard to sound chipper when bright eyes were glared at them with an unblinking, unnerving intensity. The other Sans was obviously assessing them with critical scrutiny, bouncing on the balls of his feet as if getting ready to fight.

Sans finally seemed to regain his bearings, and his left eye lit up in a roar of painfully familiar magic, looking every bit as grim as the gasterblaster that immediately formed above him. He pushed himself free of Papyrus’ nervous hold, posture bold and one hand held out in front of him protectively. The blaster’s mouth split impossibly wide as it roared directly in the face of the other Sans, bones clacking ominously in obvious warning.   

Papyrus was stunned at this unprecedented boldness. And more than a little afraid. 

Sans’ doppelganger looked equally surprised, immediately stiffening and looking up at the blaster with a strange expression that almost looked like fear. But as Papyrus rubbed his eyes to make sure he wasn’t hallucinating, the expression quickly shifted into something more determined. Not-Sans quickly tucked his jaw against his chest, pulling his elbows close to his chest. He half-curled his fists and shifted his left foot forward, fixing the blaster with an almost predatory gaze.

Sans blanched, seemingly snapping out of his aggressive spell as he looked at the other skeleton incredulously. Was this guy seriously going to try and punch his blaster? Sans could see part of an apparently well-worn knuckle duster sitting just below his lookalike’s scuffed gloves, which looked like they had dealt out a fair number of sucker punches. He absolutely could, and seemed to have every intention to do so, having hopped up on the coffee table for better leverage.

“What are you _doing?!”_  

His blaster let out a whine as it looked at this alternate Sans in obvious confusion, watching one hand pull back as if in preparation for-

"Everyone chill." The other Papyrus’ eye flared to life as the room came to a standstill, and though it wasn’t obvious exactly what he did, the other Sans looked annoyed. Papyrus wondered if his alternate somehow thwarted an attack, hands placed firmly on the shoulders of apron-wearing, angry Sans. 

“Woah, okay, time out,” Sans put his hands up in a ‘T,’ taking a step back from the alternates. He noticed the spoon from earlier on the floor, and he held it out like a peace offering. It smelled cheesy. “We’re not here to fight-”  
  
“Hah! You show up in our home uninvited, try to destroy our door and jinx the house, and now you have _that thing_ out! You don’t pull out your most powerful weapon if you aren’t expecting to use it! ” the other Sans cut-in with a tense, borderline aggressive tone, pulling against the hands trying to hold him back. 

“You grabbed my brother _by the throat_ and threw him at your fuckin’ couch! ” Sans snarled back in a tone of voice Papyrus had never heard before, posture tense and alert.

“ **You** broke into **_our_** house!” 

“Sans! Stop!”

"Standing around throwing accusations isn’t going to get us anywhere," the other Papyrus sounded tired, like this was a frequent disagreement. "Sansy, come on. We can talk this one out." He urged, bordering on pleading, trying to coax his brother off the coffee table.

‘Sansy’ looked at his brother for a long moment, before turning back to them as though gearing himself to do something unpleasant. 

“..… I will... give... you... a chance... to explain…. yourselves,” he said each word carefully and reluctantly, frequently glancing at his brother as though the words were being whispered to him. His posture still very much battle-ready and unformed magic glimmered on his fingertips, “Imposters! You have thirty seconds.” 

"Huh?" It took Papyrus a moment to realize the other Sans was addressing them, too busy inspecting his double. Reading lips was very difficult if you didn’t have them. "Imposters? I think you're the ones confused. Clones maybe, imposters seems a bit harsh-"    
  
“15-14-13-” 

“H-hey, you didn’t even start at thirty! Sans! Um, my Sans!” Papyrus reached out to gently poke Sans in the back. “Could you go back to being my extremely relaxed, lazy, and calm brother again? This active, defensive, and angry you is making the other active, defensive, and angry you nervous! And me too, for that matter!” 

Sans looked back at Papyrus guiltily, and held his hands up in the universal sign of surrender- but he made no move to dispel his blaster. Although seeing the hoodie-wearing Papyrus stand up for them eased the tension considerably, he wasn’t about to trust the guy who was counting down impatiently.  
  
“12-11-te-eeeeh-n!” Sansy’s voice rose a little bit in alarm as he was picked up, hand tightening warningly on the hands around his chest as his magic spiked erratically. He seemed to realize pretty quickly it was his brother, and he sighed in exasperation as he dispelled the bones around him with a sharp look back.  
  
“Don’t DO that, Pappy,” he grumbled irritably, eyes going back to Sans and Papyrus warily even as he settled into his brother’s arms, “I was three seconds from throwing you against that wall. You didn’t even realize your soul turned blue, did you? This is precisely why I worry- you’re so careless sometimes! ”

"Ok." ‘Pappy’ replied as though he hadn’t heard a word addressed to him, holding his brother under the arms like a pudgy cat.

Sansy sighed wearily, “Anyway, I think in this particular case the talk first and fight later approach might work, but I don’t think it should be your default.”He seemed to have decided Papyrus and Sans weren’t a threat, if he was relaxing so much, but the look he gave Papyrus was calculating. 

Sans kept quiet, but with Sansy seemingly pacified, or at least unwilling to punch him in that position, he sent his blaster back. Borborygmus still looked as confused as a Blaster could, but seemed happy enough to return back to… wherever she usually stayed. Sans took a long, deep breath, massaging the spot right above his nasal cavity.

“Neither of you have answered my questions,” Sansy started seriously, as if trying to keep an air of authority even as he was being held in the least intimidating way possible, “The facts are that you broke into our house and continue to behave in a most suspicious manner. So, give me a reason to believe you aren’t a threat.”

“Are you shapeshifters? Are you trying to take our place by looking like us? It’ll never work, you know- you’re much too active a Sans to be believable! My brother is the laziest guy around- this is unusual and alarming behavior for him! And I would never dress in something so _messy_! Maybe you could revert to your usual forms and we could sit down and talk? We’re all monsters- we won’t mind what you actually look like!” 

“What are you talking about? You’re obviously the shapeshifters here! I’m letting Pappy restrain me right now, but don’t think I can’t and won’t hurt you if you try anything!” 

“Maybe I could make you some tea to calm down? Or would you like some candy?”

Sans worked on putting himself in a better frame of mind as he scrutinized the other skeletons warily, ignoring Sansy’s intense glare as he took a closer look at their surroundings. It sure looked like their old house in Snowdin- down to the same ugly rug pattern- but at the same time very different- his living room sock was missing. The couch seemed to be on the wrong side of the door too, as though everything had swapped places. For things to be so similar and yet radically different, the only explanation was- 

“Alternate selves.” 

Papyrus inched closer to his own Sans. He could practically see the gears turning in Pappy’s head as he worked through the problem in a way scarily reminiscent to Sans. 

"...Unless Dyne's started clone research, you probably aren't from around here. Nor, judging from your initial freakout, did you mean to come here." 

Sans was impressed. Incredibly unsettled, but impressed. Well, he had been stuck in worse situations before, and at least it wasn’t Halloween here. For all his bluster, Sansy didn’t look like he was about to break free and fight them. He could work with this. Yeah.  
  
“Bingo,” Sans started to say carefully, giving the alternate universe pair a tense smile and shrug, even as he put his hands in his pockets and relaxed his posture.  
  
"Is...he implying you took us to another universe?"

Sans took a step away from Papyrus as he cleared his throat, clearly hesitating as he looked at Papyrus’ boots, “Well-”  

“What?!?!” Sansy’s expression was borderline comical, eyelights comically large as he sputtered incredulously. “You’re telling me these skeletons are us… from a different dimension?! World? Reality? Wormhole? Wha- How?!” 

“How did you even do that?! I _told_ you we should have taken my car! But no! You had to use a _shortcut!!”_

“Does that mean you can shortcut yourself anywhere?! Like into the Core, or the surface, or a warzone?! That’s really dangerous!” 

“I know!! That’s exactly what I said! See, I’m _not_ crazy to worry about that!”

“Absolutely not! Why would you _do_ that?! What, by Queen Toriel’s horns and crown, were you thinking?! You’re lucky you didn’t shortcut yourself into oblivion!”

Sans slumped further in his hoodie with a groan, flipping the hood over his head as Papyrus’ previous lecture repeated... in stereo. Sans avoided looking behind him, even as he felt his guilt crawling on his back. Sansy turned to Pappy with an odd expression, unable to smooth his apprehension even as he tried to force his expression blank.

“I told you that magic was dangerous! Apparently, you’ve been lucky!  Papyrus,“ his tone became a lot sharper and colder, almost like it was someone else entirely, “Natural aptitude and luck can

             only       take         you         so             far,

                    and        you’ve      gone        as          far         

               as         you           can         go-”

Sans felt very, very cold all of a sudden as he recalled a confusing series of memories of someone tall, commanding, and stern- no, it was someone clever and awkward - he had dark eyes and long, slender hands. He was glad he was gone- no, he desperately wanted to see him again- no, he couldn’t remember. It felt like there was a gaping hole where someone painfully familiar should be. Who could-?

_It’s rude to talk about someone who is listening,_ his mind told him in a voice not at all his own. It was smiling. It was frowning. Papyrus flinched and Pappy glanced around like there was someone else in the room. His sockets furrowed in confusion, muttering something that distinctly sounded like ‘Dad?’

“Lucky for you, you ended up here with the _magnificent_ Sans and his _cool baby brother_ Papyrus, in always sunny and always pleasant... Din Snow!” Sans jumped, looking at his counterpart oddly as Sansy burst out laughing boisterously, looking cheerful for the first time this entire encounter.

Sans had already forgotten what he had been thinking about, but the odd sensation lingered on like an itch he couldn’t scratch. 

Pappy scowled in a way that was definitely more Papyrus-like, “No one even understands your stupid joke, Sansy. Don’t listen to him, this place is called Snowdin.”

“Whatever you say, Rus-papy.”

Sans’ own smile strained a little, Sansy’s lecture still a sharp sting. “In _short_ , you could say we’re just _cutting_ through here,” he began airily, going back to his favorite defense mechanism, “But I guess you’re right- we could be in a much worse place. Someplace where they would’ve attacked on sight and not been as friendly and hospitable, right? _Bone-a-fide_ barbarians.”  
  
Sansy’s expression immediately soured, and Papyrus looked like he was going to interject, so Sans kept talking, “So, might as well make the best of this stroke of good luck, eh? So, yeah, I’m Sans and this is my brother, Papyrus, and thanks for such a _warm welcome_ to your living room.”  
  
Sans  sighed and finally looked directly at Papyrus, grin faltering and looking incredibly sheepish as he cleared his throat guiltily, “We, uh, may be here a while, Pap.”

“So....we're stuck.”

Papyrus gave Sans a long, pointed look as he allowed the statement to sink in. Point proven.

**Notes for the Chapter:**

> Next time: It's NOT Wonderwall  
>  _He opened the eye sockets he didn’t remember closing, suddenly pivoting his torso towards Sans. “I wrote a song. Want to hear it?” He didn’t wait for an answer before Pappy disappeared, reappearing a few seconds later with a guitar in hand. He spent a few seconds adjusting and testing the chords before clearing his throat._
> 
> Just a few points:  
> 1) It's Halloween in the UT Skelebro timeline, and Papyrus has enthusiastically embraced all the spooky! Everything inside and outside is positively decked out in cobwebs, fake blood, body parts, etc. That's helped put Sans on edge too!  
> 2.5) Reverse Trick or Treating is just breaking and entering, tbh.  
> 2) Our US!Sans is very different from your typical Blueberry depictions! I hope you'll still give my Sansy a chance, though. ;3  
> 3) That bit with Gaster is kinda weird, huh. I meant for it to be like.... echoing something Swap!Gaster said. Does this get explained later? Ehhh.


	2. Sansy & Pappy

**Summary for the Chapter:**

> They talk, they cook, they split up to stay inside and to go outside!

**Notes for the Chapter:**

> Long time no update! This is why you shouldn't juggle like 8 projects at once lol.
> 
> Thanks to all the nice comments and subscriptions we got for this story! :o We're glad you like Pappy and Sansy! 8D Thank you for your support and readership! <3
> 
> For clarification:  
> Underswap!Sans - Sansy  
> Underswap!Papyrus - Pappy  
> Undertale!Papyrus - Papyrus (Pap)  
> Undertale!Sans - Sans

 

“I, uh…”  
  
  
Sans visibly wilted under Papyrus’ sharp gaze, but it was undoubtedly deserved. Just as quickly, Papyrus was all smiles again, turning his back on his brother as he amicably approached their alternate selves. He was determined to make the most of the situation!  
  
  
“At least it’s a _creative_ terrible joke! Do you have any idea how many snow and skeleton puns I’ve been subjected to over the years? All of them. Every. Single. One. There really aren’t that many.“ Papyrus sighed dramatically, though his complaint was obviously in good humor.  
  
  
Sansy was a little surprised at how quickly the other Papyrus embraced the situation, tensing in Pappy’s hold as he eyed Papyrus warily. Sansy wasn’t sure how he was supposed to react to this enthusiastic, bubbly version of his brother. Pappy looked dazed, nodding dumbly at the torrent of words directed at him.  
  
  
“Anyway, I suppose there’s no helping us being late to the party but that’s no reason to be rude, so- nice to meet you, other Papyrus and other Sans!”  
  
  
Feeling ridiculous for being wary of someone as obviously harmless and friendly as Papyrus Pappy forcibly relaxed, offering a friendly smile of his own. Sansy didn’t like being loomed over, but kept his tone civil if not a bit uncertain, “Uh, it’s… nice to meet you too…I guess.”  
  
  
If Papyrus noticed the lukewarm reception of his alternates, he gave no outward indication, continuing to chat amicably. “I have an apron just like yours!”  
  
  
_That_ got to him. Sansy let out a surprised, good-natured laugh, leaning forward in Pappy’s hold to hold out the hem. “Haha, really? And here I thought it was homemade! This moron thought it’d be a hilarious gag gift, but it works for my purposes. I like the fact it’s got flames on something so pink.”  
  
  
“M-moron??”  
  
  
“ _You’re_ supposed to be embarrassed, not use it to embarass _me_ …” Pappy muttered quietly, but he reached a hand out to give Papyrus’ shoulder a reassuring squeeze. “Sansy’s got the sensitivity of a cactus, but he wouldn’t use it if he didn’t secretly like it. He’s just really embarrassed at affection- he’s afraid that’ll ruin his ‘cool guy’ demeanor.”  
  
  
“Oh!” Papyrus brightened instantly, “Well, other-Sans, I can undoubtedly reassure you that showing brotherly affection in the form of nice nicknames and compliments is a _lot_ cooler! The coolest, in fact! So do not feel the need to try and impress me with this ‘bad boy’ facade! If I’m Pappy, in some way or form, I already know you’re really cool!”  
  
  
Sansy blushed and impressive shade of blue and sputtered, “I wasn’t-! I don’t-! Wha-t-!”  
  
  
“I think your battle body is especially cool!” Papyrus continued, undeterred, determined to prove to Sansy how cool he thought he was, “I always try and get my Sans to wear his, but he just doesn't _understand_.”  
  
  
Sansy was staring at Papyrus as though he had grown another head, taking a closer look at the ‘battle body.’ Was this supposed to be armor of some sort? It didn’t look particularly made for combat- the fabric looked soft, the chest plate moved in a manner that suggested it didn’t have much DF, and he was sure those details were glued on. Was it a costume? It probably wouldn’t do very well in a fight….   
  
  
Pappy didn’t miss a beat, “Battle body, huh? Makes sense, but it’s not particularly comfortable, is it? That’s why I reached a compromise with Sansy by agreeing to wear this thin hoodie, which is better for fighting or something but isn’t nearly as uncomfortable.”  
  
  
“Battle body?” Sansy repeated to himself, scrutinizing the shoulder pads before focusing on the sleek black body suit underneath. He perked up immediately, “Hey, is that like a drysuit? ...Yeah, it is! That’s a really smart touch for both combat and environmental purposes- lightweight and flexible, but still providing protection. I like that a lot! Pappy could take some fashion pointers from you!”  
  
  
Pappy sighed.  “It’s whatever, right?  In the end, armor won’t do much against an assailant with true deadly intent, so why prolong the pain?” Pappy shrugged, failing to notice the concerned confusion in his double’s expression.  
  
  
Sansy tensed and huffed irritably at Pappy’s innocuous statement, a definite warning note in his voice, _“Pappy.”_  
  
  
“Well, I can see you both have a lot to talk about so I’ll leave you to it. Sorry on behalf of my brother, he’s not much of a monster person. Wasn’t hugged or picked up enough as a kid or something- you can help him with that, right?”  
  
  
Sansy moved to the defensive immediately, “ _Don’t_ touch me. I’m not some _doll_ you can just manhandle.”  
  
  
“ _Sansy,_ ” Pappy put a placating hand on his brother’s skull, petting him like he would a dog, “Sorry for the threats, he’s just a little wary of strangers. But seeing as you’re _me_ , I’m sure he’d love to get to know you, isn’t that right?” The swapped doubles exchanged a look before Pappy decided Sansy wasn’t going to lunge at their alternate selves and put him down.  
  
  
“Asshole…” Sansy muttered mutinously, crossing his arms when he was finally put down. He watched Pappy make his way to the other Sans, keeping a wary eye on them before Papyrus was very much in his personal bubble and demanding his full attention again.  
  
  
“I’m sorry if I offended you! I wasn’t trying-”  
  
  
“No, no, it’s fine.” Sansy held a hand up and did his best to give Papyrus a reassuring smile. He was sure he looked like he was trying too hard going by Papyrus’ dubious grin. “You guys just really startled me and I’m still kinda jittery. It’s been a not so great week- day- um, time.”  
  
  
“Oh! Were you in the middle of something?” Papyrus clapped his hands together. “Can I help you with anything? I’m a super good helper!”  
  
  
“Uh, I guess…” Sansy gestured at the kitchen and watched Papyrus run in, following at a more sedate pace. “ I was making some Mac and Cheese for dinner, and was putting the finishing touches on it. Do you like to cook?”  
  
  
“Do I!! It was part of my training for the royal guard, back in the day! I spent many an evening mastering spaghetti under the passionate tutelage of our illustrious Captain! I’ve moved onto other recipes and I’ve changed my technique since then, but I still find cooking invigorating and refreshing!”  
  
  
“Really? I’ve always thought it was kind of relaxing… Uh, but I’m not confident in my abilities, so my recipe pool is pretty limited. I tried to make a quiche once, but it was more like some weird scrambled eggs thing. At least my Mac and Cheese is… pasta-ble, mwehehe.”  
  
  
“Hey.”  
  
  
Sans stopped eavesdropping on the kitchen bustle when he felt Pappy approach him, stuffing his hands into his pockets as he nodded awkwardly, “Hey.”  
  
  
Pappy’s smile was kind, as though he knew Sans was obviously unsure what to do now that his irritated brother abandoned him, and nodded to the couch. “Want to come watch NTT TV with me? Might be nice to chill out for a bit before we start figuring out a way to get you back home. You and I should, in theory, share the same space tears so it shouldn't be too hard, but...eh. Like my alternate self said, let’s make the most of the situation right?”  
  
  
“Heh,”  Sans chuckled softly, hands still in his pocket as he regarded Pappy carefully, noting his brother’s counterpart looked almost as tired as he felt. Sitting down for a while sounded really nice. “I’m always game for cool new shows.”  
  
  
Pappy walked over to plop back down and comfortably sank into the cushions. Sans followed suite, grabbing a nearby pillow and using it to cushion his back as he slouched a little more fully. The tight coils of tension and dread in his soul seemed to unwind as he was finally able to relax a little bit, relieved at the familiarity of home and gentle, reassuring company.  
  
  
“Backache?”  
  
  
“Nah, I’m just _bone_ -tired. I could nap a _skele_ ton today.”  
  
  
_“Nyegh,”_ Pappy made a strangled noise between a laugh and a sigh, “I don’t think you’re as _humerus_ as you think, Buddy.”

 

There was a loud bang from the kitchen, and Papyrus immediately emerged with a comically infuriated expression directed at Sans. “SANS!!!”  
  
  
“What?! I just said _I_ thought it tasted better with a hot dog! I never said _you_ had to eat it that way! _Geez._ ” A disembodied voice called out from the kitchen  
  
  
Papyrus turned his head, “I meant my Sans! Since you are my brother in some shape or form too, I already assumed your diet and tastes were unsalvageable! Feel free to eat whatever culinary monstrosities you like! I’ll introduce you to real, proper food sometime when I eventually make some of my much beloved spaghetti for you!”  
  
  
There was a sound that might have been laughter, before Papyrus pointed a stern finger at the couch, “Don’t think I didn’t hear that! How dare you! I’m already angry at you, and then you had to- ugh!!! You’re awful! Two skeleton puns in one sentence! Don’t think I’m not going to put them on the board just because we’re not at home, because I! Will! Remember!!”  
  
  
Flinching at the loud and sudden outburst, it took Pappy a second to recognize the argument for being the silly, brotherly banter that it was and how much more it seemed to bother Papyrus than being teleported to another universe. He chuckled as he toyed with the toothpick in his mouth, too amused by the situation not to chip in. “It’s not quite the same, but we have a ‘board of shame’ hanging on our fridge too if you-”  
  
  
“Good! Maybe having his reputation stained by two shame boards will make him actually feel bad for doing it!” Papyrus didn’t wait for Pappy to finish before he walked back into the kitchen and made a beeline for the whiteboard on the fridge. Sansy seemed to have turned off the stove, washing some cheese sauce off of his hands… and face at the weirdly short sink.  
  
  
Papyrus picked up the marker before he blinked at the chart written in comic sans. “Mentions of mary jane...Tia wearing the shirt...any use of the number 420...jokes about joints...baking? What? I don’t understand any of these.” Regardless, Papyrus squeezed BONE TIRED and SKELE-TON onto the chart and added a tally for each. His font stood in sharp contrast to Sansy’s, but he reasoned it would be all the easier to remember for later.  
  
  
“They’re stupid and tasteless, just like Pappy,” Sansy explained with a sigh, crossing his arms as he gave his brother a pointed look, “So don’t worry about it.” He didn’t really want to explain Pappy’s ridiculous humor to anyone.  
  
  
When Papyrus joined Sansy at his new position by the door, he pointed a gloved finger at the fridge. “I hope you’re proud of yourself, because now your sins are written on several shame boards for all to see! Even if I don’t really understand this one- who is Mary Jane, and why can’t we talk about her?”  
  
  
Pappy snickered in a way that had Papyrus immediately regret asking, if not for how genuinely amused he looked. “Sansy doesn’t like how _blunt_ she is, but that’s just how she _rolls._ Personally, I think she’s pretty _dope_ because I don’t have Sansy’s _high_ expectations, but his reactions are so _high_ larious I love giving him a _bud_ time about it.”  
  
  
“Uuuuugggghhhh.” Sansy dragged his hands down his face and glared at Pappy, who just burst into laughter. He gave Sans an equally annoyed look when he started laughing too, buoyed along by Pappy’s mirth.  
  
  
Papyrus narrowed his eye sockets suspiciously. “There was a joke somewhere in those innocent sounding sentences.” He turned to Sansy sympathetically. “That was worth at least a couple tallies on the shame board.”  
  
  
Sansy nodded, giving Papyrus a long-suffering look back. Someone _finally_ understood. Sort of.  
  
  
“Hehe, is that a-” Pappy tried to keep a straight face and failed miserably. “-joint decision?”   
  
  
Papyrus noticed a similar glint in Sans’ eye as he got inspired, and turned to Sansy to exclaim loudly, “Knowing my lazy brother, we’ll probably be here for a while so- can we go outside? If this is really Snowdin, I’d love to see it again! Oh, let me tell my Sans first, hold on-” He turned his head towards his brother, just a few feet away. “SANS we’re going to go outside!”  
  
  
“Ok, Pap, have fun,” Sans answered with a lazy wave back. A little time apart would do them some good.  
  
  
“Again?” Pappy echoed, laughter morphing to confusion.  
  
  
“Huh?” Sansy raised his eyeridges, slightly bewildered, “You’re not concerned about going out to explore a strange new place? Maybe it is similar, but you can’t be sure- it could be summer outside, for all you know!  And, just you and me? Your brother is ok with this?”  
  
  
“What do you mean? I’m going to have you as a guide, and I can see frost on the windowpane! And why wouldn’t Sans be ok with me going out on my own? I’m a grown-up perfectly capable of taking care of myself and making my own choices, thank you very much! And the Great Papyrus, a responsible, mature, and completely grownbones, chooses to go outside with my alternate universe brother, Sans!”  
  
  
“Ok, ok,” Sansy held his hands out placatingly, “First things first, it’s going to be confusing calling ourselves Sans and Papyrus, so let’s settle on some nicknames. Let’s keep it simple. You guys just go by Papyrus and Sans. My brother goes by Pappy most of the time anyway, and you can call me… Sansy. I guess.”  
  
  
“Really?! You’re going to let _them_ call you Sansy? Wowie!” Sansy gave Pappy a look.  
  
  
“Those are childish nicknames- that’s what I called Sans when I was, like, 10!” Papyrus made a face, sticking his tongue out, “I want to have a cool nickname, like Cool Guy! Or Master Chef! Or Classic!”  
  
  
“I always thought Sansafrass had a nice ring.” Sans’ grin stretched wider, “Papchinko?”  
  
  
“Thanks for the input, peanut gallery, this isn’t a democracy. Papyrus, Sans, Pappy, and Sansy it is.”  
  
  
Papyrus gave a deep sigh, looking off to the side dramatically, “I _guess_ … Now can we go outside, Sansy?!”  
  
  
“Eh,” Sansy scratched at his cheek nervously, trying to avoid looking at Papyrus directly as he felt a puppy dog stare start to crumble his resolve. He couldn’t leave Pappy alone because of… something bad. Something really bad would happen if he left Pappy alone. But he wouldn’t be alone if Sans was with him. Sans would protect and look after Pappy like he would his own brother, right? “I don’t… know…”  
  
  
Papyrus couldn’t wait for Sansy to stop wrestling with his overprotectiveness, walking over to the door and pulling it open to look outside. He squealed in absolute delight at the sudden gust of cold air, running his hand along the door jam fondly. “Just as I remember it! Except- oh, you don’t have lights outside, you have tinsel! Why do you have tinsel outside? Where are the lights?!”  
  
  
“Sansy.”  
  
  
He startled at the sound of his name, looking up at Pappy sharply. His brother gave a small, reassuring smile, as though he could tell what Sansy was worried about, before he allowed it to drop. “Promise me you won’t pick any...fights, while you’re out. Please.”  
  
  
“What!” Sansy huffed indignantly, turning on his heel irritably and stalking to the door, turning to stick his tongue out at as almost an afterthought. That was the only answer he was going to get- there was only one opponent he was currently focused on, and there was no way he was going to let them pass unchallenged. And if Pappy was concerned he was going to pick a fight with Papyrus-!  
  
  
“Sans!” he called out irritably,“Fine. I’ll take care of Papyrus, and you take care of Pappy.”  
  
  
Pappy frowned as he turned away, glowering at the TV as he toyed with the stick in his mouth. Sans glanced at Pappy, before gently punching his shoulder, “The way this day’s going, he’s gonna be the one keeping _me_ outta trouble.”  
  
  
Sansy didn’t look particularly convinced or reassured, but Papyrus was literally tugging him out the door at this point. “Yes, yes- Oh, and Sans! Please do not let your new pun pal distract you from actually finding a way out of here! We’re late enough for this party as is!”   
  
  
“Ok, ok- I’ll _snow_ you all of DinSnow’s scenic stops then,” Sansy paused at the doorway, giving Pappy a meaningful look, “Don’t take any shortcuts.”

**Author's Note:**

> Thank you for reading! We're very excited where this story is going, and we hope you enjoy it as much as we are!


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